If that is out, then so is just about every other way to track them in an accurate way. Any system used is going to need equipment in close vicinity to track the movements accurately. Units I was suggesting can be as small as a stack of a couple (3/4) small coins and have a range of several hundred feet to a mile or two depending on what your receiver is capable of. This would be a very minor footprint compared to some other possible systems that will require several pieces of equipment around each monitored stone. A UAV could also be used to circle the playa for several hours every couple of hours as another option. That would also provide a minimal footprint if flown high enough but it would also be costly and at risking a crash, seems less advisable.

Ralph, very nice paper. My niece works for the Nature Conservancy and she suggested that it may be easier to get permits to do experiments on dry lakes under the management of BLM as their mission focuses on multiple land uses. She sent links to two very nice photos of Racetrack Playa

Reading your paper Ralph it looks like the occurrence and duration of ice is still being debated.

Indeed. I think much of the literature has been unfortunately cast in black-and-white terms'Ice is essential'... 'Oh no it's not'...'oh yes it is' etc..... (qv Sharp and Carey, Reid et al., etc.)

The reality is likely more nuanced - my take is that large rocks require ice, and that for most large-scale movements (i.e. when many rocks move) ice is involved. But small rocks can occasionally movewithout the help of ice sails (or more particularly, ice rafts). I suspect too that there is a spatial element to it - the south end of the playa where most of the rocks are delivered to the playa surface from the cliffs is also probably the area most often shadowed by same cliffs when the sun is low in the sky in winter. So the south end is more likely to see ice than the north.

But all this is qualitative handwaving without quantitative data (as Kelvin sortof said). It may be in part that the problem has mostly been studied by geologists, who as a tribe (this is fightin'talk, I know) may be less inclined to apply probabilistic (or even quantitative) approaches to the problem.

To remedy this deficiency, our efforts over the past few years at least now provide somebasis for discussion on occurrence and duration of water and ice on the playa. Also, whileit is all very well for someone to figure out that winds of X speed can move a rock of Y mass without ice, there has really been only handwaving 'this is reasonable/not impossible' etc.Can such winds occur often enough to explain the trails we see ?

Well the rocks move slowly so it took a few years since the last post, but a nice paper is out in PLoS One. Ralph and other authors have have a great movie capturing rock movement. LinkTitle: Sliding Rocks on Racetrack Playa, Death Valley National Park: First Observation of Rocks in Motion

I was very lucky to have seen the rocks move myself. What is interesting to me (in an introspective way)is how the problem has connections with so much of my 'day job' - wave generation, wind-blown drift of the TiME capsule, evaporation rates, playa geomorphology, etc. etc.

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